Pelvic relaxation or pelvic organ prolapse is an important cause of morbidity in aging women. An association between parity and pelvic relaxation has been accepted; however, the etiology of prolapse in women is not clearly understood. To evaluate parity and age as risk factors for pelvic relaxation and prolapse, we have established three groups of two year old female monkeys under three different breeding conditions; with intact male, with vasectomized male, and with no male. All females are nulliparous at the beginning of the study. Pelvic examinations and measurements, photographs, pelvimetry, and body measurements have been made bi-annually. These groups will continue to be followed. By delaying the age of first pregnancy in two groups, we will be able to compare parity, age and mating without pregnancy as factors contributing to pelvic relaxation and prolapses.